The present invention relates to the preparation of allylated poly(vinyl chloride) by utilizing an allyltrialkylsilane in the presence of Friedel-Crafts acids. The pendant allyl groups can be further reacted through various functionalization reactions to contain groups such as epoxy. A method for determination of the labile chlorine content of poly(vinyl chloride) is also disclosed.
During polymerization of vinyl chloride to poly(vinyl chloride) (PVC), in addition to regular xe2x80x94CH2CH(Cl)xe2x80x94repeat units, a very small quantity of xe2x80x9cactivexe2x80x9d or xe2x80x9clabilexe2x80x9d chlorines also arises. Although the concentration of these active chlorines is very modest, their presence decisively influences the ultimate thermal, oxidative, and chemical stability of this commercially important resin. The literature is replete with references addressing details of this problem such as set forth in Thermal Degradation of Some Model Compounds for Poly(vinyl chloride), Airinei, Buruiana, Robila, Vasile and Caraculacu, Polymer Bulletin 7, 465-471, (1982); Formation of Anomalous Structures in PVC and Their Influence on the Thermal Stability:1 Endgroup structures and Labile Chlorine Substituted by Phenol, Hjertberg, Soervik, J. Macromol. Sci., Chem. 1982 A17(6), 983-1004; and Formation of Anomalous Structures in PVC and Their Influence on the Thermal Stability:2. Branch Structures and Tertiary Chlorine, Hjertberg and Sorvik, Polymer, Vol. 24, June, 1983, pp. 673-684.
It has been found that the active chlorines in poly(vinyl chloride), in conjunction with certain Friedel-Crafts coinitiators, are efficient initiators for the grafting of cationically active monomers (isobutylene, styrene) from poly(vinyl chloride), and that the thermal stability of the grafted poly(vinyl chloride) increases significantly over that of unmodified poly(vinyl chloride). See for example Cationic Grafting: The Synthesis, Characterization and Physical Properties of Poly (Vinyl Chloride-g-isobutylene), Kennedy and Davidson, J. Macromol. Sci. Chem., A12(2), pp. 197-207 (1978); Poly(vinyl chloride-g-Styrene): Synthesis, Characterization, and Physical Properties, Kennedy and Nakao, J. Macromol. Sci.-Chem., A12(2), pp 197-207 (1978); Thermal Stability of Graft Modifications of PVC and Related Materials, Abbas, Journal of Polymer Science: Polymer Chemistry Edition, Vol. 13, 59-68 (1975); New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers). XVII. Epoxy and Aldehyde Telechelic Polyisobutylenes, Kennedy, Chang, and Francik, Journal of Polymer Science: Polymer Chemistry Edition, Vol. 20, 2809-2817 (1982); and New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers). III. Synthesis and Characterization of a Poly(xcex1-Methylstyrene-b-isobutylene-b-xcex1-Methylstyrene), Kennedy and Smith, Journal of Polymer Science: Polymer Chemistry Edition, Vol. 18, 1539-1546 (1980).
The active chlorine content in poly(vinyl chloride) has been determined by several groups by using FTIR and UV spectroscopy, and selective reactions in conjunction with IR- or UV- active reagents. The values reported in the literature cover quite a broad range (i.e. anywhere from 0.04 to 2.3 mol %), and the discrepancy cannot be explained only by the differences between the samples used. This uncertainty prompted us to develop an analytical method for the determination of the minute concentrations of active chlorines in poly(vinyl chloride) starting material.
The preparation of the allylated poly(vinyl chloride) is described herein. The active chlorines in poly(vinyl chloride) can be replaced by pendant allyl groups (xe2x80x94CH2CHxe2x95x90CH2) by the use of allyltrialkylsilane in the presence of Friedel-Crafts acids. The thermal stability of allylated poly(vinyl chloride) is significantly superior to that of the starting material. NMR analytical results of the allylated poly(vinyl chloride) can be utilized to determine the active chlorine content in poly(vinyl chloride). The allyl groups of the allylated poly(vinyl chloride) can be used in various functionalization reactions such as epoxidation, hydroboration, and hydrosilation.